Answer:

These diagnostic codes indicate a problem with one, or more, of the EPROM’s. This IC could be missing, not properly seated in its socket, or defective. Below is a table matching the EPROM’s to their respective diagnostic codes:

U800: E1111, E1112

U900: E1121, E1122

U810: E1131, E1132

U910: E1141, E1142

U820: E1151, E1152

U920: E1161, E1162

U830: E1171, E1172

U930: E1181, E1182

Due to the age of these products, replacement parts are no longer available.